Intractable poly(p-phenylenebenzobisthiazole) fiber

ABSTRACT

Poly(p-phenylenebenzobisthiazole) (PBT) fiber which is at least partially insoluble in methanesulfonic acid at room temperature. The fiber is prepared by heat treatment of PBT fiber, for a time sufficient to make it at least partially insoluble in methanesulfonic acid, at temperatures of 550° C. (e.g., for 600 seconds) to 780° C. (e.g., for 18 seconds).



